| Title | Formation Cleaning in Reinjection Wells: Learnings From New Zealand Field Trials |
|---|---|
| Authors | Alan Ferguson |
| Year | 2026 |
| Conference | World Geothermal Congress |
| Keywords | formation cleaning, formation scale, geothermal reinjection well, well recovery |
| Abstract | Oversaturation of silica in separated geothermal water (SGW) can lead to scaling in reinjection wells and the formation around these wells. Wellbore scaling is best dealt with through mechanical means; however, formation scaling requires a different treatment. These deposits in the formation are typically dealt with by applying chemicals to the formation to remove part or all of the scale and recover reinjection capacity. To understand historic cleans and identify the best chemical make-up for future jobs, we have undertaken a research project in the last couple of years to build on our previous knowledge. Following on from this extensive research programme studying the literature, previous results and conducting laboratory testing, we have begun to test our findings in the field. This paper outlines the successes, learnings and future outlook of our reinjection well formation cleaning programme. Through our field trials we have uncovered useful information on the importance of selecting an appropriate volume and concentration of chemical to increase the chances of a more successful result. We will share our observations on how the application of the chemical can affect the amount of scale removed and the overall efficacy of the clean. The initial efforts we have undertaken to improve the decline rate post-clean will also be discussed. |